1. Field of the Invention
The present invention relates to a semiconductor device including a semiconductor chip and a lead which are electrically connected to each other via a bonding wire. The present invention also relates to a method for making such a semiconductor device.
2. Description of the Related Art
Electrically connecting a semiconductor chip and leads of a lead frame by using bonding wires is conventionally known. Examples of the shape (loop shape) of such bonding wires are as disclosed in e.g. JP-A-11-67809 and Japanese Patent No. 2823454.
FIG. 61 shows a principal portion of the semiconductor device disclosed in JP-A-11-67809. The semiconductor device 90 shown in FIG. 61 includes a semiconductor chip 91 having a bonding pad 911, a bonding wire 92, and a lead terminal 93 connected to the semiconductor chip 91 via the bonding wire 92. The bonding wire 92 includes a first portion 921, a second portion 922 and a third portion 923. The first portion 921 has a shape extending upward substantially vertically from the portion press-bonded to the bonding pad 911. The second portion 922 extends horizontally from the first portion 921 to reach a position close to an end of the semiconductor chip 91. The third portion 923 extends downward front the second portion 922 to the portion bonded to the lead terminal 93.
The bonding wire disclosed in FIG. 2 of Japanese Patent No. 2823454 is connected at one end to a bonding pad of a semiconductor chip and connected at the other end to an inner lead of a lead frame at a position close to its end. The loop of this bonding wire has a triangular shape.
In recent years, the distance between a die pad and a lead tens to be reduced in accordance with size reduction of semiconductor packages. Thus, to avoid contact of the bonding wire 92 with the semiconductor chip 91 in the semiconductor device 90 for example, the inclination angle θ of the bonding wire 92 with respect to the lead terminal 93 needs to be increased. Specifically, the inclination angle θ is set to about 60 to 80°. With such an arrangement, however, wire sweep may occur in molding the resin package or the bonding wire 92 pushed up due to thermal expansion of resin may be detached from the lead terminal 93, which may cause an increase in defective rate.
To solve such a problem, it may be considered to lower (down-set) the position of the die pad on which the semi conductor chip 91 is to be mounted. However, in view of thickness reduction of the semiconductor package, down-setting the die pad is not desirable. Moreover, down-setting the die pad is sometimes difficult due to the structure of the device.
Also, there is another problem. In the semiconductor device 90, a plurality of bonding wires 92 similar to the illustrated one are used, and each of the bonding wires extends linearly as viewed in plan. In this case, the bonding wires need to be spaced apart from each other by a certain distance to avoid contact between them. However, such an arrangement hinders size reduction of the semiconductor device 90.